The principle and algorithms of independent component analysis(ICA) is illustrated. The paper introduces virtual channels and  the virtual structure of multichannel, to complete a singletrial estimation of singlechannel pattern PVEP, which overcomes the problem of using ICA directly to singlechannel signals. Compared with the average technology, its encouraging results are illustrated by both computer simulation and clinical data applications. The number of trials needed is reduced to one. By analyzing the time course and spatial pattern of the independent components, a certain component is  found to be closely related with the P100 latent period in the VEP complex.